Why We Collect an Outdoor Baseline Sample During Mold Testing

Every DezAir mold test includes an exterior sample alongside interior sampling, and it's a step that sometimes raises a reasonable question: why test outside if the concern is inside the home?

Why the Outdoor Sample Matters

The answer is that mold spores exist naturally in outdoor air everywhere — they're part of the normal environment, not a sign of a problem.

Without knowing what's naturally present outside a specific property on a specific day, an indoor spore count on its own doesn't tell you much. Is an indoor reading of a certain level high, normal, or low?

That depends entirely on what's typical for that location and that day, which is exactly what the outdoor sample establishes.

The Outdoor Sample as a Baseline

The outdoor sample becomes the comparison baseline:

• If indoor mold spore types and concentrations are similar to or lower than the outdoor baseline, that's generally a reassuring sign — it suggests indoor air isn't harboring an elevated mold source beyond normal ambient levels.

• If indoor levels are significantly higher than outdoor, particularly of species not well-represented outside, that's a more meaningful signal of an actual indoor source.

Why Mold Testing Isn't Pass or Fail

This is also why mold testing results aren't simply a pass/fail number — a lab report showing "some mold spores present" isn't inherently alarming, since some level is universal and expected.

The comparison to the outdoor baseline is what turns a raw number into an interpretable result.

Schedule a radon or mold test today with DezAir Quality Testing online at dezairqualitytesting.com.